Mechanical properties and plastic deformation behavior of severely deformed pure Fe

Recent developments of severe plastic deformation techniques enable to fabricate ultra-fine grained materials with a grain size below 1 μm. The important features of ultra-fine grained material is superior strength–ductility balance. In this study, ultra-fine grained pure Fe was prepared by high-pressure torsion process, and their mechanical properties was investigated by tensile test. It was found that the ultra-fine grained sample fabricated by high-pressure torsion shows large uniform elongation whereas the annealed sample barely shows. The neutron diffraction measurement during tensile test revealed that grains in the ultra-fine grained pure Fe show no orientation dependence during deformation, meaning every grain accommodates plastic strain uniformly.